Most work vessels are barges and are held with mooring lines or are dynamically positioned. Mobilization and demobilization of these conventional work vessels are done dockside, which takes several weeks and ties up the vessel. Furthermore, conventional work vessels are specifically designed to perform a narrow group of tasks. Even further, each vessel must itself be seaworthy. Therefore, when the tasks that the vessel is designed to do are not in operation, the vessel experiences down time. Down time is costly.
Thus, there is a long felt need for a modular system, which is cost effective, able to perform a large number of tasks, and requires shorter mobilization and demobilization times.
The problems described above are addressed, according to one example embodiment of the invention, with a work module support vessel that is designed to carry, on its deck, various types of work modules. Each type of work module performs a specific set of tasks. This allows the work module support vessel to perform a wide range of services used in construction and maintenance activities for offshore oil and gas operations.
In one example embodiment, an offshore construction system is provided. The system comprises a work module support vessel and a pontoon-supported work module. The work module is designed to perform a specific set of tasks related to offshore oil and gas operations in open waters. The work module support vessel carries on its deck one or more pontoon-supported work modules and is capable of ballasting down a sufficient depth to allow the pontoon-supported work modules to float over the stern portion of the deck of the vessel and be positioned on guide rails at selected points. The support vessel is equipped with a jacking system to skid the work modules on and off the support vessel.
In a further embodiment of the present invention, an offshore construction system is provided. The offshore construction system comprises a work module support vessel having a ballast-down mode, in which a deck of the work module support vessel is submerged, and a ballast-up mode, in which the deck is above water. The system further comprises a pontoon-supported work module carried on the deck of the support vessel. The system further comprises a draw connected between the work module and the work module support vessel having a draw-over mode, in which the work module is drawn over the deck, and a remove mode, in which the work module is removed from the deck.